Phone to Tablet Remote can connect with Bluetooth or Wifi and works with these apps:
AIMP, Amazon Music, Apollo, Apple Music, BlackPlayer, Deezer, Default Music Player, doubleTwist, Eleven, Equalizer Plus, Google Play Music, HTC Music, jetAudio, Just, Miui, Music Player, Music Player for Android, Music (Sony), N7 Player, Napster, Neutron, Noozy, Pandora, Phonograph, Pi, Pixel, PlayerPro, Poweramp, Pulsar, Rocket Player, Samsung Music, Shuttle, Soundcloud, Spotify, Stellio, VLC, Winamp, and Youtube (see below).
If your favourite app is not listed, you can just enter its package name to control it.
PAID VERSION BENEFITS:
The paid version of the app lets you control playback with buttons in the notification area and from the lock screen. It only costs $0.99 (79p).
There are three methods you can use to connect your devices.
1. Wifi Network (e.g. home network):
Select the "Wifi Network" option when first starting the app. On the player device, press the "Run Server" button. An IP address and port number will appear. On the remote device, press "Run Remote", enter the IP address and port number of the server, and press "Connect". Playback buttons should then appear.
Make sure your devices are paired via Bluetooth. Select the Bluetooth option when first running the app. On the device which will be the remote control, select the device you want to control from the list, then press "This Device is the Remote". After a few seconds, playback buttons should appear.
3. Wifi Direct:
Select Wifi Direct when first running the app. On both devices, press "Scan for Devices" simultaneously. When scanning is finished, select the device you want to control from the list of devices on the remote device, and press "This Device is the Remote". After a few seconds, playback buttons should appear. (Can sometimes take a bit longer).
To switch between connection methods, open the settings from the menu, and look under "Connection Options". The first setting lets you choose between Wifi and Bluetooth. When Wifi is enabled, there is a further option to enable Wifi Direct.
When connected, you can choose which app you want to control from the dropdown list, and use the buttons to control playback. You may need to open the player app on the playback device first.
Select "Find playlists" from the menu on the remote and the app will import all the playlists it can find from your playback device. Choose the one you want, and the track listing will show on your remote. Although all of your playlists should show up, Phone to Tablet Remote can currently only play them back with four music player apps: Poweramp, Google Play Music, Rocket Player, or the Android internal player.
When controlling the YouTube app, the back and next buttons only work if you are watching a playlist. Also, the play/pause buttons only work if you have already started playing a video.
If the app you use for playback is not in the dropdown list of music players, simply select "Custom 1" from the bottom of the list. Then go to the playback device, open Phone to Tablet Remote, and from the menu in the top-right corner, select "Set custom app packages". In the space for Custom app 1, enter the package name of the app you want to control, and press OK. You should then be able to control the app.
You can use an app like Package Name Viewer to get the package name of the app you want to control.
Pressing the back button when connected doesn't quit the app, it just minimises it. To quit, first disconnect by selecting "Disconnect" from the menu, then press back to fully quit.